The Columbia Population Research Center (CPRC) seeks Research Infrastructure FY 2014 (P2C) funding from the Population Dynamics Branch at NICHD/NIH (RFA-HD-14-016). We request $1,297,874 in direct costs over the five-year period beginning September 1, 2014. The CPRC has four primary research areas: (1) children, youth, and families, (2) gender, sexuality, health, and HIV, (3) immigration/migration, and (4) urbanism. Research in these four areas is united by two cross-cutting themes: (1) the health and well-being of vulnerable populations; and (2) the formation, implementation, and evaluation of public health and social policies that address these vulnerabilities. Our goals are to: (1) nourish a vibrant intellectual community of population researchers at Columbia University; (2) advance population research in our four signature areas; (3) become a leading population center specializing in research on the health and wellbeing of vulnerable populations locally, nationally, and internationally, and on public policies relevant to those populations; and (4) take advantage of Columbia's location in New York City, both to address issues specific to or aggravated by its status as a global city, and also to exploit and further develop the many partnerships between Columbia researchers and local academic, city, and international institutions. We will accomplish these goals through three research infrastructure cores: Administrative, Computing and Methods, and a Development Core. The latter will foster cross-disciplinary and cross-campus research linkages among Columbia faculty whose work advances those goals. The CPRC is co-directed by Irwin Garfinkel, Mitchell I. Ginsberg Professor of Contemporary Urban Problems in the Faculty of Social Work, and Constance A. Nathanson, Professor of Sociomedical Sciences and of Population and Family Health in the Mailman School of Public Health.